During the coming year clinical studies will continue on the selection of patients with chronic ventilatory insufficiency for diaphragm pacing. Emphasis will be placed on the evaluation of diaphragm pacing in patients with central alveolar hypoventilation and quadriplegia. A study will be made of the causes of upper airway obstruction in patients selected for diaphragm pacing and a study of the loss of hypoxic drive in patients with ventilatory insufficiency requiring diaphragm pacing will be continued. The influence of diaphragm pacing on pulmonary hypertension during sleep will be studied. A registry of all patients with diaphragm pacemakers will be maintained. Experimental and clinical evaluation of phrenic nerve stimulation on diaphragm function will also be evaluated both experimentally and clinically. Clinical application of a demand-type diaphragm pacemaker will be expanded. In the animal laboratory in vivo testing of a hermetically sealed capsule for implant of RF components will be started. The experimental application of a totally implantable diaphragm pacemaker in the study of several stimulating waveforms will be done. The prototype of a total implantable pacemaker programmable from the exterior for human application will be constructed. A quantitaive study of tissue perfusion by heat loss calorimetry will be expanded. BIBLIOGRAPHIC REFERENCES: Glenn WWL, Holcomb WG, Shaw RK, Hogan JF, Holschuh KdeR. Long-term ventilatory support by diaphragm pacing in quadriplegia. Ann Surg 183:566, 1976. Hogan J, Holcomb WG, Glenn WWL. Programmable, totally implantable, battery-powered diaphragm pacemaker. Biotelemetry 2:81, 1976.